Compressor construction



June 14, 1966 D. K. EMMERMANN ETAL 3,

COMPRESSOR CONSTRUCTION Original Filed April 14, 1961 3 Sheets-Sheet l umvs oar/0s ALEXfl VDEP 242cm arramvsrs l United States Patent "ice 3,255,602 COMPRESSOR CGNSTRUCTION Dieter K. Emmermann, John Hans Davids, Wallace E.

Johnson, and Alexander Zarchin, Beloit, Wis., assignors to Desalination Plants (Developers of Zarchin Process) Limited, Tel Aviv, Israel, a limited company of Israel Continuation of application Ser. No. 103,115, Apr. 14, 1961. This application July 8, 1964, Ser. No. 381,946 21 Claims. (Cl. 62123) This application is a continuation application of application, Ser. No. 103,115, filed Apr. 14, 1961 and now abandoned.

This invention relates to an improvement in fluid-displacement devices and more particularly relates to an improved fluid compressor provided for operation under subatmospheric pressure conditions. The apparatus of the present invention is hereinafter described in connection with a system for producing sweet water from sea water, but it must be appreciated that the inventions are capable of application to other fields.

My associates and I have delevoped a system for desalination which produces large volumes of sweet Water economically, and this is the subject of our copending US. patent application, Ser. No. 103,114 filed Apr. 14, 1961 for Methods, Systems, and Apparatus for'Separating Solute in Substantially Pure Form From Solutions, which is hereby incorporated herein by reference.

This application relates to the construction and arrangement of the compressor utilized in this system. In this system sea water is flash-evaporated in a lowpressure evaporating chamber to form pure water vapor, pure ice, and concentrated brine. The compressor withdraws the vapor from that chamber and delivers it to a low-pressure condensing chamber where the vapor and ice are brought together to condense the vapor and simultaneously melt the ice to produce the final sea-water product.

As will hereinafter appear, a compressor of this type for use in vacuum-freezing systems must move and handle a large volume of vapor at low pressure, will be of great size and have a rotor which operates at high speed. The compressor is subject to low pressure at both its intake and discharge outlets. It is important that the impeller be as light as possible, because of the speed at which it operates.

Accordingly, an object of the invention is to provide a compressor of improved, simplified, economical construction. A further object is to provide such a compressor which can operate under subatmospheric pressure conditions.

Another object is to provide an improved compressor for a vacuum-freezing system, for delivering vapor from the evaporating chamber into the condensing chamber.

Another object is to provide an improved compressor rotor assembly.

A still further object is to provide an improved compressor rotor assembly, including rotor blades of thin sheet material flexibly mounted on a central hub wherein the thin rotor blades assume operative positions due to centrifugal forces.

Another object is to provide an improved compressor rotor construction which can handle large volumes of vapor and yet is of relatively lightweight construction.

These and other objects and advantages will become more readily apparent as the description proceeds and is read in conjunction with the accompanying drawings, in which:

FIG. 1 is a schematic layout of a desalination system.

. be produced for each pound of water vapor.

FIG. 2 is an elevational view in section of the com- PICSSOI' and compressor I'OlZOI.

3,255,602 Patented June 14, 1966 FIG. 3 is an enlarged, detailed view of the connection between the rotor and blades; and

FIGS. 4 and 5 are detailed views of a compressor blade.

GENERAL DESCRIPTION OF THE SYSTEM The desalination system, with which the compressor of the present invention is used, it shown as a general layout in FIG. 1, the novel compressor being disposed in the upper central portion of FIG. 1. -The general arrangement of this system will be first briefly described.

Sea water, which is at ambient temperature, and which has been filtered to remove floating material and other solids is brought into the system through sea water inlet pipe 10 and passes through deaerator 12 where dissolved gas is removed from the sea water. The sea water is then delivered by pump 14 to heat exchanger 16, where the incoming sea water is placed in heat-exchange relationship with the potable water final product and concentrated bn'ne being withdrawn from the system.

The sea water entering the system will-be normally at ambient temperature, such as for example 77 F. and normally contains about 3.5% by weight of salt.

The sea water leaving heat exchanger 16 will be at a temperature of approximately 302 F. and is delivered through pipe 18 into the evaporating chamber 20. The sea water enters the evaporating chamber at the central hub of a distributor 22 and the water thereafter flows downwardly over depending sheets on the distributor so that the incoming sea water has a large surface exposure for evaporation.

The interior of the evaporating chamber 20 is maintained at a low pressure, approximately 3.2 mm. Hg (millimeters of mercury), by a vacuum pump not shown. Due to the fact that the interior of the evaporating cham-, ber is at such low pressure, sea water will flash-evaporate therein. At the freezing temperature of sea water, the heat of vaporization is approximately 1074 B.t.u. per pound and the heat of fusion of ice is about 144 B.t.u. per pound. As vapor is produced by evaporation, heat is removed from the remaining liquid and ice is formed therein. Due to the differences in heat of vaporization and heat of fusion, approximately 7 /2 pounds of ice will The ice so produced is substantially pure water ice with no appreciable amount of salt, contained therein. When continuous operation is established, the temperature within the evaporating chamber will be approximately 248 F. The vapor formed will be pure water vapor. Thus, upon removal of the pure water from the incoming sea water by the vaporizing and freezing, the remaining sea water becomes a more concentrated salt solution.

While theoretically in excess of pure water by weight could be removed in the form of vapor and ice, we have found that removing approximately 50% by weight of pure water is in the range of greatest efficiency; thus, if approximately 50% of the water is removed as vapor and ice, the remaining brine solution will consist of approximately 7% by weight of salt.

The evaporation of water, with the consequent formation of vapor and ice, is a function of time since'heat must be transferred, and also the rate of evaporation is proportional to surface area. remain in the evaporating chamber for a suflicient period of time and to offer large surface exposure of the sea water, the distributor 22 is disposed within evaporating chamber 20.

The brine, with the ice crystals therein, is withdrawn from the bottom of evaporating chamber 20 through pump 24, and this mixture has a temperature of approximately 24.8 F. The mixture is delivered to separator washer or counter washer 26, in which the ice is separated from the concentrated brine and the ice is washed In order to have the sea water free of salt adhering to the surface of the ice crystals. The ice-brine mixture enters the lower end of the separator-washer under pressure and the column of the separator-washer becomes essentially full of ice crystals. The pressure exerted by the entrance of the brine at the bottom of the counter-washer forces the cylinder of ice packed therein upwardly, and this brine forces its way through the ice pack, out through screens 28. A pump 30 removes the brine from jacket 32 around the lower end of the counter-washer. The pressure drop, created by forcing brine through the ice pack within the column, exerts a force on the column of packed ice moving it upwardly. Thus, the ice column within the counterwasher continuously moves upwardly. At the upper end thereof is a motor-driven scraper or wiper 34 which wipes off the top of the upwardly moving column of ice and delivers the ice into trough 36. Spray heads 38 are provided at the top of counter-washer 26 for spraying sweet water supplied by pipe 40 onto the top of the porous column of ice, which water runs downwardly over the advancing column of ice to wash away any adhering brine on the surface or in the interstices of the ice.

Sweet water is added by means of pipe 42 to the ice in trough 36 so as to produce a solution of sweet water and ice suspended therein which can be pumped.

By supplying sweet water to the ice to provide a liquid with the ice suspended therein, the resulting material may be more readily handled, and the liquor prevents the breaking of the vacuum within the vacuum chamber. Ice-sweet water pump 44 is shown for delivering the material through pipe 46 to a plurality of trays 48 arranged concentrically within a condensing chamber 50.

Condensing chamber 50 is an annular chamber, having its inner dimension defined by the wall of the concentric evaporating chamber 20 and its outer dimension defined by the outer wall 52, which preferably is insulated as indicated in FIG. 1 to prevent heat from entering the system.

The radial compressor 54, generally indicated at 54, which forms the subject of this application, is positioned Within the upper end of condensing chamber 50 and has an axial intake opening 56 in communication with evaporating chamber 20 and a circular outlet 58 communicating with condensing chamber 50.

Vapor formed in evaporating chamber 20 is drawn into central inlet 56 of compressor 54 and delivered radially outward into condensing chamber 50 through outlet 58. The vapor is thus compressed and compressor 54 maintains condensing chamber 50 at a pressure of approximately 4.6 mm. Hg. The vapor delivered by the compressor into the condensing chamber passes downwardly into contact with the ice disposed in trays 48 and simultaneously causes the vapor to condense and ice to melt. The sweet water thus produced is Withdrawn from the lower end of condensing chamber 50 through pipe 60, which delivers a portion of the sweet water back to counter-washer 26 through pipes 40 and 42 for ice washing and for mixing with the ice. The majority of the sweet water product passes through pipe 62 to heat exchanger 16.

One of the greatest difficulties encountered in prior art vacuum freezing systems is their inability to efficiently and economically handle and transport the large volumes of vapor that exist for any system producing a meaningful amount of sweet water, particularly when it is recognized that we are dealing with such low pressures that approximately 4,500 cubic feet of vapor at these pressures is required to provide one pound of water vapor. Without the arrangement and apparatus of this invention, expensive and extremely large compressors, shrouds and conduits would be required for handling the vapor. Normally, to move any such large volume, a multi-stage axial compressor would be required and the cost of the impellers and housings without considering the conduit size and expense would make the system uneconomical.

Additionally, by positioning the compressor within one of the chambers, the pressure differential across the shroud is so slight that a very inexpensive shrouding may be used on the compressor. In essence, the housing of the vessel into which the compressor discharges is the real structural support housing of the compressor.

Likewise, with the arrangement proposed, the compressor serves as a self-regulator upon the system since the amount of vapor that can be handled by the compressor will control the rate at which vapor is formed by vaporization and the rate at which it is condensed.

Ideally, the vapor should be delivered to the evaporating chamber at saturation conditions of pressure and temperature so that the vapor will condense on the 32 F. ice and the ice will take out of the vapor 1,074 B.t.u. per pound of vapor condensed and thereby cause the 32 F. ice to melt by each pound absorbing 144 B.t.u. However, due to losses because of heat entering the system and super-heating of the vapor, secondary refrigeration coils 64 are provided in condensing chamber 50. These coils condense enough vapor to provide thermal balance in the process. The coils 64 are cooled by a conventional refrigeration unit 66 in which sea water, tapped from sea water inlet 10, may be circulated and then discharged through waste outlet 68.

The motor 70 for driving the compressor is located outside of condensing chamber 50 so that it will not introduce heat into the system, and the drive mechanism between the motor and the compressor is of a unique type. Motor 70 is flooded with water delivered to the motor housing by pump 72 through pipe 74 and this water is circulated through the motor housing and discharged through pipe 76. This drive mechanism provides an effective seal for the drive shaft of the compressor, without the use of expensive and elaborate mechanical seals, which are normally required for such high pressure differentials by allowing leakage of sweet water from the motor housing into the compressor. Sweet water flowing in the motor housing cools the motor and that portion of the sweet water leaking into the compressor flash-evaporates to cool the compressed vapor and partially reduce the super-heat in the vapor.

As previously described, the final product, potable water, is delivered from condensing chamber 50 through pipe 62 to the heat exchanger 16 and is at a temperature of approximately 32 F. The concentrated brine which has been separated from the ice in counter-washer 26 is delivered via pump 30 to the heat exchanger through pipe '78 and is at a temperature of approximately 24.8 F.

The purpose of the heat exchanger is to cool the incoming sea water to the maximum extent possible by withdrawing heat therefrom and delivering it to the cold brine and sweet water produced, and it is important that the sea water be cooled as efliciently as possible. With heat exchanger 16, approach temperatures of about 2 F. have been achieved and, thus, sea Water entering the system through cold sea water pipe 18 is at about 30.2 F.

The sweet water, as it leaves heat exchanger 16 through pipe 80, is the principal product of this system and is delivered to storage tank 82 from which it may be withdrawn for use. The warmed concentrated brine, as it leaves heat exchanger 16 through pipe 84, is delivered to the waste outlet 68 for return to the sea or for other use or disposal.

' It should be noted that a higher pressure is necessary in the condensing chamber than in the evaporating chamber because the vapor pressure of the freezing brine is lower than the vapor pressure of the ice-water mixture at 32 F. The vapor pressure of brine of 7% by weight salinity at 24.8 F. is about 3.2 mm. Hg, while the vapor pressure of ice-water mixture at 32 F. is amout 4.6, mm. Hg. The compressor maintains this condition.

It has been found advisable to recirculate a portion of the cold brine in order to prevent ice from building up within the evaporating chamber and thereby plugging the system and stopping continuous operation. Thus, a portion of the cold brine taken from counter-washer 26 is delivered by pump30 into pipe 86, which connects with a tube 88 of the distributor 22, which has a spray head 90 disposed at the bottom thereof in the evaporating chamber. Likewise, a portion of the cold concentrated brine is delivered by pump 30 through brine pipe 78 and intermediate pipe 92 to' incoming cold sea water pipe 18. Thus, cold concentrated brine 'is mixed into incoming sea water and passes through the evaporating chamber 20 over distributor 22, and this mixture is joined at the bottom of evaporating chamber 20 by sprayed-in concentrated brine from spray head 00. This introduction ofconcentrated brine with the sea water does not interfere adversely with the evaporation and formation of vapor and ice, but conversely does prevent ice from building up on distributor 22. In addition, small ice crystals escaping from the drainage area of the counter-washer are thus reintroduced into the system to promote crystallization. Also, the greatest amount of ice is present in the ice-brine mixture at the bottom of evaporating chamber 22 and there is a tendency for ice build-up at that point. However, the introduction of additional brine increases the fluidity of the total mixture and also has a-fiushing action at the bottom of the evaporating chamber.

In any commercially successful desalination system, relatively large volumes of potable water must be produced and, while this may be efiected by building larger and larger equipment, again, Within shadow of commercial unacceptance due to high cost, the size of the equipment must be reasonable. With the system, schematically shown in FIG. 1, it is contemplated that approximately 60,000 gallons of potable water per 24- hour day Would-be produced. Rather than attempt to increase the size of the equipment and thereby add to its expense out of proportion to gain, it is contemplated that when larger production of potable water is required, which will normally be the case, separate but parallel systems will be installed and operated to supply additional requirements.

By referring to FIG. 2, it will be seen that compressor 54 is disposed within the outer housing of the condensing-evaporating chambers. In the particular embodiment, the compressor is disposed immediately below cover 110 of chamber 50 and above cylindrical walls 94 of evaporating chamber 20. The compressor is actually supported by this cover and comprises a housing or shroud 134, having a top housing 136 and a lower housing or shroud 138, which are secured together but spaced apart around the periphery of the compressor by attachment means 140. Bottom shroud 138 is provided with the previously mentioned central inlet 56, and the annular space between the top and bottom shrouds, extending completely around the compressor, provides the circular outlet 58 previously identified. Shrouds 136 and 138 are so sealed to the walls of the chambers that the only communication between the chambers is through central inlet 56, the interior of the compressor, and circular outlet 58. Mounted within housing 134 is a rotating impeller 142 and it is important to note that this impeller is bearinged within and supported by the top cover 110 of condensing chamber 50. The housing 134 does not journal or support the impeller 142 and the housing is a lightweight shroud fully supported by cover 110, which with the other walls is the effective support and heavy-duty housing for the compressor. As seen in the drawings, the shroud or housing 134 is of thin, light construction. Impeller 142 comprises a plurality of radially extending blades 144 and central hub 146 and is rotated by motor 70 within housing 134. It must be appreciated that in order to move the volume of vapor 6 required, this compressor is large and rotates at a relatively high speed. For example, the diameter of impeller 142 will be approximately 7 feet and the speed of rotation will be 3,600 rpm. For such speed of rotation and size of impeller, it is, therefore, most important that a strong and yet lightweight rotor be provided. Since cover is a substantial structural member, it is able to aiford the necessary support and provide a primary housing while the actual shroud or covering of the impeller is of relatively light material. In essence, the chamber into which the compressor is discharging serves here as the housing for the compressor and support for the drive.

While the system is operating and the compressor is rotating, vapor formed within evaporating chamber 20 is drawn into central inlet 56, and is moved by rotating blades 144 radially outward at progressively increasing pressure for ultimate discharge through circular outlet 58 into condensing chamber 50. In other words, the compressor affords a direct radial path for movement of the vapor. Important also is the fact that vapor will be drawn into the compressor throughout the entire area of central inlet opening 56 and discharged throughout the entire area of circular outlet 58. Thus, vapor will be delivered around the entire annular area ofcondensing chamber'50 for movement into contact with the ice that has been spread out within substantially the entire area of the condensing chamber. With this concentric chamber and compressor arrangement, vapor will move from all points of discharge from the compressor in a spiral path downwardly through the condensing chamber maintaining the high velocity imparted to the vapor by the compressor. Since condensation is a function of surface contact and velocity of relative flow, this is, of course, advantageous. The advantages of the arrange ment with regard to size and cost of equipment must be emphasized and appreciated and this close-coupled relationship of the compressor and chambers accomplishes these advantages. If a conventional volute type casing for a compressor were utilized, its diameter would be about 14 feet and to convey the volume of vapor contemplated for the type of equipment shown, ducts having diameters of approximately 6 feet would be required. Equipment of this size obviously introduces thermal losses into the system and the cost of the parts and of insulation becomes substantial.

To a large degree vacuum freezing desalination systems have heretofore been penalized because of the failwe to provide efiicient and economical equipment for and arrangements of the compressor and condensing and evaporating vessels. With the arrangements contemplated in the past to move such a large volume of vapor, one would normally use an axial compressor having several stages. The cost of such a compressor arrangement alone, and certainly when combined with the cost of providing evaporating and melting vessels, would most likely exceed the permissible cost for an entire system for desalination.

COMPRESSOR CONSTRUCTION Referring first to FIG. 2, as before indicated, the presently improved compressor generally indicated at 54 is particularly suitable for use in the aforementioned potable Water-producing system. Compressor 54 is mounted in the upper zone of the chamber 50 and overlies the upper end of evaporating chamber 20 with its intake port 56 open to chamber 20. The compressor discharge outlet 58, peripherally thereof, is directly open to the condensing chamber 50. i

As shown by FIG. 2, the compressor 54 is an axial intake, radial discharge unit of improved and compact construction. It includes a two-part housing or casing 134 of metallic or non-metallic material, as suitable sheet metal of corrosion-resistant character or suitable plastic, fiber glass, or other similar material, comprising anupper wall-forming member or housing 136 of circular periphery, and a lower member or shroud 138, also of circular periphery and spaced from the upper member to form the rotor chamber 164 therebetween. Assembly connection of the members 136 and 138 is made by a plurality of attachment means and spacer elements 140 relatively spaced about the peripheral region of the housing in connection to the respective peripheral end portions 166 and 168 of the members. Such end portions define therebetween the compressor discharge outlet 58 which is open circumferentially of the housing. Member 138 is formed to provide a wall 170 of predetermined shallow frusto-conical form between the generally radial end portion 168 and an out-turned circular flange 172, the latter defining the axial inlet eye or intake port 56 of the compressor. The upper member 136 is formed to provide a similar but oppositely directed shallow frustoconical wall section 174 inwardly from its generally radial end portion 166, merging into the inner wall section 176 which lies in a radial plane normal to the rotor axis of the compressor. Thus, in sectional view (FIG. 2), the two wall sections 170 and 174 converge toward the discharge outlet 58 from a zone which, in the present example, is slightly radially beyond the inlet flange 172. While the described frusto-conical Wall section 174 is preferred in member 136, this member could be provided as a uniformly flat or planar member with corresponding increase inthe angle of taper of the lower wall 138. The compressor housing is mounted within the upper end of the device in a horizontal position over the cylindrical wall side 94 of evaporating chamber 20, Wall 94 providing a circular central aperture 178 to receive the compressor inlet flange 172 therethrough. Support of the housing is effected from the top wall or cover 110 as by bolting at 180 to a plurality of tank strengthening ribs 182 depending from top wall 110. As shown in FIG. 2, the lower housing member 38 includes an external, depending annular flange 184 which seats in cornpressive engagement with resilient seal element 186, of rubber or the like, carried in an annular channel 187 on the outer overhanging margin 190 of the end wall 192 of chamber 20. Each rib 182 terminates in a lateral projection forming a pad against which the flange 166 of the compressor housing wall 134 abuts, such pad serving to effect the desired assembly location of the wall. Due to the vacuum in the chambers, considerable load will be exerted on cover 110 to cause deflection thereof, but since compressor 54 is supported and carried thereby, no problems to the compressor result from this deflection.

Referring to FIGS. 2 to 5, operative in the housing as above described is a compressor rotor assembly or rotatable impeller 142 comprising a hub structure 146 on a vertical drive shaft 196, and a plurality of generally radial blades 144 projecting from the hub. The hub structure comprises a shaft-mounting sleeve hub 198 keyed to, pressed on, or otherwise fixed to drive shaft 196 and held thereon as by a retainer plate 200 bolted to the shaft, and a blade hub 202 here constructed in mating halves, secured as by bolts 204 to the flange portion 206 of shaft hub 198. Formed in the hub 202 are a plurality of circular through bores 208 parallel to the shaft axis, these being inwardly adjacent to the hub periphery and equi-angularly spaced circumferentially of the hub. Each bore 208 has a radial slot 210 of predetermined width, opening the bore to the hub periphery, the slots as well as the bores being open at each side face 212 of the hub. The bores and slots form blade mounting seats.

Each blade 144 is formed from a strip of sheet material having a predetermined thickness. The blade material here used is corrosion-resistant metal, as stainless steel. In blade formation, an elongate rectangular strip of predetermined length and width is lengthwise reversely turned or folded upon itself, folding being about a round bar or arbor (not shown) at the strip center, to provide a blade of two-ply or double thickness character having the blade plies 214 and 216 and a hollow circular enlarged or eye portion 218 at one end. The blade plies are suitably secured together in flat engagement over the lengths thereof, as by a suitable adhesive or cementitious material preferably in a layer 220 between the plies. The blade over its outer end section 222 is marginally cut or reduced to provide converging blade margins 224 such that the blade will have a running clearance in the converging zone of the compressor housing formed by the wall portions and 174, FIG. 2.

In blade assembly to the hub 202, each blade has its enlarged or eye end 218 inserted and seated in one of the hub bores 208 with the blade projecting outwardly therefrom through the associated bore slot 210. The outer diameter of blade eye 218 is such as to effect a snug fit thereof in the bore, While the width of the bore slot 210 is such as to closely confine the blade portion extending therethrough. In final assembly, each blade is retained against lateral displacement from its bore seat, by suitable means as a headed bolt extending through the blade eye 218, with the bolt head 228 against one side face 212 of the hub, and a nut 230 at the opposite or threaded end of the bolt engaging against a hub closure plate 32 abutting the opposite hub side 212.

The blades 144 thus mounted on hub 202 extend therefrom in the compressor housing rotor chamber 164 with the reduced or convergently tapered and portions 222 thereof in close running fit in the converging zone of the housing provided by Walls 170 and 174. These rotor blades being constructed of thin sheet strips in the manner described, afford lightweight flexible blades which, mounted as shovsm and described, permit high-speed operation of the rotor. The two-ply blades have a predetermined minimum thickness, as for example approximately tWo-hundredths of an inch (.02") in a blade having a length of about thirty-one (31) inches and a width of about nine (9) inches inwardly of its tapered end. This minimum thickness is sufiicient for structural self-support of the blades in displacing water vapor under the heretofore indicated subatmospheric pressures, as the blades, being flexible, will assume positions of radial extension from the hub under the influence of centrifugal forces thereon in compressor operation. Thus, the improved rotor structure is one which may be economically constructed with easy-to-fabricate blades and a simple yet highly effective blade-mounting arrangement. The thin blades of stainless steel, formed in the manner described, facilitate desired high-speed rotation of the rotor and such high-speed operation is further facilitated by the absence of rotating blade shrouds.

The compressor as herein illustrated and now described, is designed and fully effective for handling water vapor in large volume and at a relatively low compression ratio, under the described sub-atmospheric pressure conditions. In this construction, the opening size or diameter of the compressor inlet eye 56 is determined in accordance with the desired velocity of vapor intake and flow rate in the compressor. As illustrated in the present example, the inlet is of relatively large diameter and open to the blades over approximately the inner half-lengths thereof. Also, since the degree of vapor compression is dependent on rotor speed and the outer diameter of the rotor blading, these factors are selected here to attain the desired compression ratio suitable to the purpose of the system referred to.

It is to be noted that the straight peripheral portions or margins 166 and 168 of the compressor housing, defining the compressor outlet 58 which is open circumferentially of the compressor, form a diffuser wherein the dynamic energy of the discharged vapor is converted to static pressure. Such difiuser may be extended to form a continuation of compressor housing wall member 138 and, cooperating with the adjacent top portion 110, provides a downwardly directed annular outlet into condensing chamber 50.

From the foregoing, it will be seen that the compressor and compressor rotor is of extremely simple and efficient construction and yet of economical construction. The rotor assembly has blades of thin sheet material in a fiexible mounting on a central hub and can handle large volumes of vapor at a relatively low compression ratio under the given suba-tmospheric pressure conditions with the blades assuming operative positions responsive to centrifugal force.

This application describes the presently preferred embodiment of the invention and is shown in connection with a system for produ ing potable water from sea water, but, of course, the invention has uses in other fields for other purposes and various changes and substitutions may be made in the particular apparatus or its arrangement without departing from the scope of the invention as defined in the following claims.

We claim:

1. In apparatus for separating a solvent in substantially pure form from a solution and in which vapor is formed and is moved from one chamber to another chamber, the improvement comprising a compressor for so moving vapor including a rotor having a hub carrying a plurality of spaced flexible rotor blades extending therefrom, each of said blades being flexible to an extent sufficient to respond to centrifugal forces acting thereon during rotation of the rotor to assume operative vapor moving positions of substantially radial extension during operation of the com pressor.

2. in freezing apparatus for separating a'solvent in substantially pure form from a solution and in which the vapor is moved from one chamber in which ice and vapor are formed to another chamber, the improvement comprising a compressor for so moving vapor between said chambers including a rotor having a hub carrying a plurality of spaced flexible rotor blades extending therefrom, each of said blades being flexible to an extent sufiicient to respond to centrifugal forces acting thereon during rotation of the rotor to assume operative, vapor-moving positions of substantially radial extension during operation of the compressor.

3. The improvement of claim 2 wherein said compressor is located between said chambers.

4. The improvement of claim 2 wherein said compressor is disposed in one of said chambers.

5. The improvement of claim 4 wherein said compressor has an outlet opening directly into said condensing chamber.

6. The improvement of claim 2 wherein said compressor arrangement is a radial compressor.

7. The improvement of claim 6 wherein said compressor arrangement includes a two part housing comprising a first wall forming member and a spaced second wall forming member, the second member having an intake port opening directly into said first compartment, the compressor blades being carried by the hub in the space between said members, and the outlet of said compressor being the space between said members defined by the peripheries of said members, said outlet opening directly into said second compartment.

3. The improvement of claim 7 wherein the first member has a circular periphery and is formed to provide a wall of predetermined shallow frusto-conical configuration between the center and the periphery thereof, and the second member has a circular periphery and is formed to provide a wall of predetermined shallow frusto-conical configuration between the periphery thereof and a centrally located out-turned flange defining an axial intake for the compressor opening into the first compartment.

9. The improvement of claim 7 wherein one of the compartments is within the other, and including a cover for the outer compartment, and means carried by the cover for supporting the housing members in said outer compartment.

Id. The improvement of claim 9 wherein the second housing member is supported solely by the first housing member.

11. The improvement of claim 7 including a motor located exteriorly of said compartments having a shaft extending into one of said compartments for driving a rotor carrying said hub.

12. The improvement of claim 2 in which said chamber in which ice and vapor is formed is an evaporating chamher and the other chamber is a vapor condensing chamber.

313. The improvement of claim 2 wherein said chambers are coaxial and contiguous.

1 The improvement of claim 13 wherein one of said chambers is partially disposed in the other.

15. The improvement of claim 2 wherein said'chambers are concentric.

16. The improvement of claim 15 wherein said chambers are coaxial and contiguous.

17. The improvement of claim 2 wherein said compressor and chambers are coaxial and contiguous.

18. The improvement of claim 2 wherein said compressor and chambers are concentric.

19. The improvement of claim 18 wherein said compressor and chambers are coaxial and contiguous.

26. The improvement of claim 2 wherein said compressor and chambers are coaxial and contiguous and one of said chambers is partially disposed within the other.

21. The improvement of claim 2 wherein said one chamber is a vacuum freezing chamber for producing ice and vapor of the solvent.

References Cited by the Examiner UNITED STATES PATENTS 1,035,364 8/1912 Le Blanc 230l33 1,426,954 8/1922 Brooks 230134 3,103,792 9/1963 Davids 62l23 3,136,707 6/ 1964 Hickman 202-236 3,175,372 3/1965 Anderson 62l23 ROBERT A. OLEARY, Primary Examiner. 

1. IN APPARATUS FOR SEPARATING A SOLVENT IN SUBSTANTIALLY PURE FORM FROM A SOLUTION AND IN WHICH VAPOR IS FORMED AND IS MOVED FROM ONE CHAMBER TO ANOTHER CHAMBER, THE IMPROVEMENT COMPRISING A COMPRESSOR FOR SO MOVING VAPOR INCLUDING A ROTOR HAVING A HUB CARRYING A PLURALITY OF SPACED FLEXIBLE ROTOR BLADES EXTENDING THEREFROM EACH OF SAID BLADES BEING FLEXIBLE TO AN EXTENT SUFFICIENT TO RESPOND TO CENTRIFUGAL FORCES ACTING THEREON DURING ROTATION OF THE ROTOR TO ASSUME OPERATIVE VAPOR MOVING POSITIONS OF SUBSTANTIALLY RADIAL EXTENSION DURING OPERATION OF THE COMPRESSOR. 